Balancing Act

As women age, vitamin D shortage and frailty become more prevalent. Weakness and slowness are potential results of vitamin D deficiency.

Many experts recommend measuring vitamin D levels in older adults and prescribing supplements if necessary. However, a new study finds a U-shaped relationship between vitamin D levels and frailty, meaning too much or too little can have adverse effects linked to frailty. According to the study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism, older women with vitamin D levels higher than 30 ng/ml and those with levels lower than 20 ng/ml were more likely to be frail. Researchers looked at vitamin D levels and assessed frailty status in a cohort of 6,307 women aged 69 and older.

"Vitamin D supplementation has grown in popularity, yet the association between vitamin D status and risk of adverse health outcomes in older adults is uncertain," said Kristine Ensrud, MD, professor of medicine and epidemiology, Minneapolis VA Medical Center and the University of Minnesota and lead author of the study. "Our study did not find that higher vitamin D status was associated with lower subsequent risks of frailty or death. In fact, higher levels of vitamin D were associated with increased likelihood of frailty."

Some 4,551 women classified as non-frail at baseline had their frailty status reassessed an average of 4.5 years later. The results? Older women with vitamin D levels less than 20 ng/ml and more than 30 ng/ml had higher odds of frailty at baseline. Lower vitamin D levels among non-frail women at baseline were associated with an increased risk of frailty or death at follow-up.

"Evidence is lacking to support use of vitamin D supplementation for prevention of frailty and other outcomes including cancer or all-cause mortality," said Ensrud. "Our results indicate that well-designed large randomized trials of sufficient duration are needed to accurately quantify health effects of vitamin D supplementation, including whether or not supplementation reduces the incidence or progression of frailty in older adults."